Shell cases



L. HEIDMANN Dec. 20, 1960 SHELL CASES 5 Sheets-Sheet 1 Filed Feb. l2.1957 MOLD WALL |Iv w L.HEIDMANN Dec. 20, 1960 SHELL CASES 3 Sheets-Sheet2 Filed Feb. l2, 1957 3 Sheets-Sheet 3 United States Patent O SHELLCASES Leon Heidmann, Paris, France, assignor to Forges et Ateliers deConstructions Electriques de Jeumont, Paris, France, a corporation ofFrance Filed Feb. 12, 1957, Ser. No. 639,673

Claims priority, application France Mar. 4, 1952 l6 Claims. (Cl. 102-43)This invention relates to shell cases and other containers of like shapeof the type described in my co-pending applications No. 292,321, filedJune 7, 1952, now abandoned, and No. 491,943, led March 3, 1955, nowabandoned, of which this application is a continuation-inpart.

The invention consists of improvements in shell cases or containershaving a multi-layer wound tube or tubular body portion and to animproved and novel method of manufacturing them. Heretofore design andmanufacturing engineers have been faced with the complex problems ofdesigning and manufacturing shell cases that have a suitable factor ofsafety and yet enough elasticity to return to their original dimensionsafter removal of the stresses developed by the rapidly expanding gasesthat tend to deform a shell case radially when a gun is fired. Theelastic limit of the materials used must be such that no permanent setremains so that the shell case may be easily automatically gas-expelled,manually removed or otherwise mechanically ejected from the gun.

Moreover, as the speed of targets increases, the guns used to fire atthem have their firing rate increased and the ejection problem is mademore difficult due to the elevated temperatures encountered when a gunres many rounds in succession. Furthermore, ease and speed of ejectionbecomes important in order to permit increased firing rates with safetyin that the bore and breech must be cleared7 between the firing ofsuccessive rounds to preclude hang fires etc.

While shell cases made of a winding of sheet metal secured to a basehave in part been an answer to the above problems, since they permitrelative movement of the layers to effect radial expansion of the shellcase; cases thus constructed have limitations in that some of them willpartially unwind due to impacts that they may be subjected to, as forexample, in being transported during operations in the field. Moreover,if the shell case is of the type secured to a deformable base bypositioning one end of the winding, comprising a tubular portion, into agroove in the base and then subjecting the assembly to a high internalfluid pressure while in a mold an additional limitation is encounteredin that rejects will be found since some cases will unwind after moldingoperations.

It can readily be seen that fastening or securing the layers inmulti-layer wound shell cases by the known methods of welding, riveting,and by tenons not permitting relative movement between the layers doesnot solve the problems and shell cases so constructed are subject to theabove mentioned problems of the possibility of surpassing the elasticlimit of the material so that removal of the expended shell case from aguns breech may well be made impossible after ring.

It is a principal object of the invention to provide a shell caseovercoming all of the above mentioned problems and limitations of theknown types of shell cases.

Another object is to provide a shell case simple and inexpensive tomanufacture and permitting present equip- Fice ment to be used toconstruct or manufacture shell cases according to the invention.

Still another object is to provide a method of manufacture withoutadding to the labor cost of manufacture by requiring additionaloperations.

A feature of the shell case in accordance with the invention is that atleast one arcuate radially projecting prominence is automatically formedon an inside layer of the multi-layer tubular portion of the shell caseduring a final molding operation and is slidably engaged with a recessor aperture in an adjacent layer or with a corresponding prominence toreleasably lock the layers in fixed relationship regardless of the typeimpact or shock to which the shell case is subjected. The locking meansis unlocked only by radial forces having a predetermined value to permitsliding relative movement between the layers whereby the elastic limitof the material used in constructing the shell case is never reached orexceeded due to the above mentioned radial forces. The elasticity of theassembly is thus maintained permitting easy removal of the shell caseafter firing.

Other objects, features, and advantages of the invention will beunderstood from the following description and claims in conjunction withthe accompanying drawings which illustrate, by way of example, preferredembodiments of the shell cases, and in which Fig. 1 is a verticalsectional view of the assembled shell case inside a mold and illustratesthe molding operation in accordance with the invention.

Fig. 2 is a schematic cross-section View of the shell case taken on linez-z of Fig. 1.

Fig. 2a is a fragmentary cross-section View of the shell case materialbefore fluid pressure is applied.

Fig. 3 is a plan View illustrating the geometry of the sheet materialbefore being wo-und into the tubular portion of the shell case.

Fig. 4 is a fragmentary cross-sectional enlarged view of the releasablelocking means, according to the invention, in locked position.

Fig. 5 is a fragmentary cross-sectional enlarged view of the releasablelocking means of Fig. 4 shown in unlocked position.

Fig. 6 is a fragmentary vertical sectional view of a triple layer shellcase locking means according to the invention.

Fig. 7 is a fragmentary cross-sectional View of the locking means shownin Fig. 6 and taken on lines 7-7.

Fig. 8 is a vertical sectional view of an assembled triple layer shellcase and illustrates a construction wherein the locking or connectingmeans of the invention is not visible externally.

Fig. 9 is a transverse sectional view taken on line 9-9 of Fig. 8.

Fig. l0 is a fragmentary vertical sectional view of an assembled shellcase and illustrates another embodiment of the locking means accordingto the invention.

Fig. 11 is a fragmentary transverse sectional view taken on line 11-11of Fig. 10.

Fig. 12 is a fragmentary vertical sectional view of an assembled shellcase and illustrates another modification 0f the locking means and themethod of forming it.

Fig. 13 is a fragmentary cross-section view taken on line 13--13 of Fig.12.

The shell case in accordance with the invention comprises a multi-layertubular portion A fixed to a base B (Figs. 1 and 8) by means of aninturned end t fixed in a frusto-conical groove as shown. The tubularportion A is formed by rolling a sheet of metal a having a trapezoidalform (Fig. 3) or any other suitable geometry, so that edge e ispositioned internally (Fig. 2) forming an internal helical seam and edgeg is positioned external of the winding forming a helical lap joint orseam. The sheet of metal a is provided with an aperture or hole ypositioned toward the edge g and adjacent the marginal portion t asshown. The hole y is thus adacent the external helical seam formed byedge g and near the base in the finished shell case.

The lower marginal portion t is bent inwardly by known means and themulti-layer winding of sheet material forming the tubular body of theshell case is assembled with the base B made of a deformable material.The assembly is then placed in a mold M (Fig. l) where a high uidpressure is applied to the interior of the case to mold the case to thesize and shape of the mold. During the molding operation the effect ofthe internally applied uid pressure is to move the layers of the windingoutwardly radially against the mold walls so that the tubular portion ismolded to its finished shape and dimensions as determined by the moldwalls. During the course of the same operation and immediately after themolding of the shell case, the inner layer a1 (Figs. 1, 2a, and 4) has alocalized area corresponding with the aperture or hole y deected ordeformed outwardly to automatically form `an arcuate radially projectingprominence or protuberance penetrating into the hole or recess y. Thusit can be seen that the layer a2 more particularly the hole y cooperateswith layer al to form a rounded protuberance x of such a size as to becapable of sliding movement in said hole or recess y to provide anelastic interlock between the layers to restrain unwinding of the sheetin the manner later herein described.

It will be understood that the fastening or layer interlocking meansmust be releasable only by non-localized internal forces appliedinternally of the case or container in radial directions and outwardlydirected and must permit circumferential displacement of the layers bymovement relative one another in order to meet the conditionsencountered in the ring of a gun.

The invention functions as follows:

When the gun is fired the hot and rapidly expanding gases tend to expandthe shell case radially so that layer a1 moves circumferentially in thedirection of the arrow f1 (Fig. 5) and the layer a2 movescircumferentially in the direction of arrow f2 until the inner walls ofthe gun breech (not shown) limit any further movement. As the gaspressure diminishes the inherent resiliency of the material and thegeometry of the rounded protuberance x move the layers in an oppositedirection back into an interlocking position as shown in Fig. 4.Accordingly it can be seen that the arcuate configuration of theprotuberance x releasably locks the layers so that during the relativesliding movements of the sheet layers in opposite circumferentialdirections the elastic limit of the material from which the shell ismade is never reached much less exceeded. Accordingly the shell casereturns to its initial dimension permitting it to be easily ejected orremoved from the gun breech. It will be understood that hole y may beprovided with a chamfered edge as shown in Fig. 5 in order to facilitatethe above described circumferential movement of the layers and an easyreturn of the prominence x into registering position with hole y so asto interlock the layers.

It has been found and verified during the course of extensive officialtests, wherein twenty thousand rounds were fired, that shell cases madeaccording to the invention never once were hard to extract or eject fromthe guns in which they are fired. Inspection of the shell cases afterfiring proved the functioning of the mechanical interlocking means inthat score marks were found on the inner side of the layers a2 showingthe extent of the movement of the prominence x during the slidingdisplacement of said layers. The tests proved conclusively that thenovel construction of the shell cases resulted in a shell case thatcould easily be removed after firing and offered no limitations as tomanual, mechanical or automatic ejection means and the only limitationon the rate of firing would be the ejection means itself. Accordingly itcan be seen that the new and novel interlocking means overcomes theheretofore mentioned limitations in both shell cases made either bywindings or by drawing. Moreover, the layer interlocking means isnormally in a locked position and maintains the layers in xedrelationship when subjected to impacts and vibrations encountered duringtransportation. The tests disclosed that release of the interlockingmeans is possible only as heretofore described by internally appliedradial forces.

It will be understood that the sheet metal employed in making the casesmust have sufficient rigidity so that the prominence x is not crushed ordeformed by the firing pressures and particularly when in an unlockedposition as shown in Fig. 5 wherein the layers are subjected to elevatedpressures while being held against the walls of the gun breech. Thus itcan be seen that material while being deformable must not be so easilydeformed that attening of the prominence x would be permitted under theabove conditions when firing. Furthermore the material must not bereadily deformable so that a new prominence is formed in the layer a1when the hole y is displaced (Fig. 5) relative to the initial prominenceformed by the high uid pressures used in molding. In order to satisfyall these requirements the sheet material must be deformable andelastic, as for example, a soft steel sheet having a thickness of theorder of 0.5 mm. The diameter of the hole or recess y must not exceed afew millimeters in order that the deformation or prominence x isproperly dimensioned so as to have sufficient mechanical strength toresist crushing when subjected to compression forces during ring asheretofore described.

While the releasable layer interlocking means has been described ascomprising a single hole y and a registering and interpenetratingdeformation, therein providing a mechanical interlocking of the layersto restrain unwinding of the sheet material forming the tubular portionof the case, it will be understood that a plurality of holes andregistering prominences can be employed. Where only one hole is used itis preferable to position it as shown in Fig. 3 so that it is near thebase and because of the helical outer lap joint or seam the entirelength of the seam is effectively held by the one fastening means. Ithas been found that positioning the fastening means near the open end ofthe shell case permits partial unwinding near the base.

The invention is applicable to shell cases wherein the tubular portioncomprises more than two layers, as for example, as shown in Figs. 6 and7 wherein a case is made of three layers a0, a1, and a2. The hole y ismade Without chamfered edges and is positioned in the outer layer a2 sothat the two inner layers are deformed radially to form thenterpenetrating prominences x1 and x2 registering with the hole y asshown. The operation of the fastening means both in the locked andunlocked position is similar to the locking means described with respectto Fig. 4.

Moreover, if it is desired to position the mechanical interlock so thatit is not visible on the external periphery of the container or shellcase the hole y may be positioned in the intermediate layer a1 (Figs. 8and 9) so that the registering deformation is formed in layer a0 asshown. Accordingly the mechanical interlock cannot be seen from anexternal position since outer layer a2 has no discontinuities.

While the invention is directed at a novel mechanical interlockparticularly applicable to pressure containers, as for example, shellcases the invention also provides a simple and inexpensive process ofmaking said shell cases without resort to tooling-up with new tools andalso permitting the use of existent molding equipment. Accordingly themanufacturing process provides means wherein the mechanical interlock isformed simultaneously with the final molding operation of the shell caseinter-locking the layers so that the shell case retains its finishdimensions. Moreover, even though the invention has been described ascomprising the deformation of a rounded protuberance into a holeprovided in the sheet material for making the shell case it will beunderstood that the layer fastening means may comprise an inwardlydirected radial deformation. Thus prior to winding the sheet ofdeformable material n a deformation n can be provided therein positionedso that it will be disposed on the intermediate layer al (Figs. and 11)so that the deformation n cooperates with the intern-al pressure whenapplied to produce a local registering deformation on the innermostlayer a0. The registering deformations comprise a mechanical interlockoperating in a similar manner to the mechanical interlock meansheretofore described. If it is desired to form the mechanical interlockwithout performing any operations prior to the molding operation thehole y and deformations n may be replaced by a forming means p made ofan incompressible material so as to form a localized mechanicalinterlock as shown when a high fluid pressure is applied to the interiorof the case and mold.

Thus it can be seen that a novel method is provided wherein meanscomprising a hole, a prominence or forming means is positioned betweenthe inner layer of the deformable sheet material and the mold wall tocooperate with a high fluid pressure to form a releasable mechanicalinterlock in an improved shell case.

While preferred embodiments of the invention have been illustrated anddescribed, it will be understood that the invention is in no way limitedto these embodiments and that many changes may be made within the spiritand scope of the invention as defined by the following claims.

What I claim and desire to secure by Letters Patent is:

1. An open-ended shell case having a base provided with an annulargroove in one face, a multi-layer tube consisting of wound deformableelastic sheet material and having an external helical seam, meansholding one end of said tube clamped in said groove, the other end beingfree, the improvement which comprises, means providing a slidablemechanical interengagement of superposed layers of said tube comprising,in a part of said layers, local radially oifset portions slidablyengaged in an interlocked position by corresponding recesses in adjacentlayers adjacent said helical seam and near said clamped end to provide areleasable elastic interlock between superposed layers having theirnormal diameters and to restrain unwinding of said sheet, said oifsetportions forming rounded protuberances of such shape as to be capable ofelastic movement in said recesses in opposite circumferential directionsof said shell case to permit momentary radial expansions of said tubeduring tiring without crushing said rounded protuberances of said tubeand to produce after tiring its contraction into the interlockedposition by contraction due to the elastic character of said sheetmaterial, and the configuration of said protuberances and recesses beingso chosen as to facilitate the elastic return of the case layers to theinterlocked position.

2. An open-ended shell case comprising, in combination, a base having inone face an annular groove, a multilayer tubular body portion having ahelical seam and consisting of a winding of deformable and elastic sheetmaterial having the characteristic of retaining a deformation, one endof said tubular body portion being fastened in said groove to join thebody portion and base, a releasable mechanical interlock for providing aslidable mechanical interengagement between said layers to restrainunwinding of said sheet material, said interlock comprising at least onelocal radial substantially arcuate and rigid prominence formed on atleast one of the inner layers of said tubular body portion and the layersuper` posed over said inner layer being provided with a recess adjacentsaid helical seam and near said base, said recess registering with saidprominence and slidably en gaging it in an interlocked position, wherebysaid shell case tube is radially expanded during firing when an internalpressure of a selected value obtains in said shell case for overcomingresistance oifered by the interengagement of said prominence with saidrecess so as to move said layers circumferentiallyl relative oneanother, grid is radially contracted to the interlocked position afterring.

3. A shell case according to claim 2, in which said tubular body portioncomprises three layers, and in which said recess comprises Ia holeprovided in an intermediate layer and said slidable prominence isdisposed in the innermost layer, whereby said mechanical interlock isnot visible from outside of said shell case.

4. A shell case according to claim 2, in which said tubular body portioncomprises at least two layers and the layer having said recess comprisesthe outermost layer defining the outer periphery of the shell case bodyportion, and in which said recess comprises a hole, said slidableprominence terminating substantially iiush with the outer periphery ofthe tubular body portion of the shell case.

5. A shell case according to claim 4, in which said hole has edgesdefining its dimensions and said edges are chamfered.

6. An open-ended shell case comprising, in combination, a base having inone face an annular groove, a multilayer tubular body portion having ahelical seam and consisting of a winding of deformable and elastic sheetmaterial having the characteristic of retaining a deformation, one endof said tubular body portion being fastened in said groove to join thebody portion and the base, a releasable mechanical interlock forproviding a slidable and elastic interengagement between said layers torestrain unwinding of said sheet material, said interlock comprising aplurality of local registering yand interpenetrating radial deformationsdirected in an inward direction, said deformations comprising rigid andsubstantially arcuate prominences positioned on the inner layers of saidbody portion and having an offset dimension large enough to otterresistance to relative sliding movement of said layers in oppositecircumferential directions by all forces below a tirst selected valueand to non-localized forces internally applied and radially andoutwardly directed below a second selected value, whereby said shellcase is radially expansible only when an internal pressure having avalue greater than said second selected value obtains in said shell casefor overcoming resistance offered by said registering andinterpenetrating deformations so as to permit momentary expansion ofsaid case during firing without crushing said protuberances of said tubeand to produce its elastic return into the interlocked position aftertiring by a suitable elastic force.

References Cited in the file of this patent UNITED STATES PATENTS 42,329Crispin Apr. 12, 1864 818,731 Adriance et al Apr. 24, 1906 2,193,573Tackler Mar. 12, 1940 2,397,206 Ryan Mar. 26, 1946 2,397,370 Raven etal. Mar. 26, 1946 2,611,460 Nash Sept. 23, 1952 2,853,945 Stealey Sept.30, 1958 FOREIGN PATENTS 519,001 France Jan. 14, 1921 826,272 FranceJan. 4, 1938 731,748 Germany June 7, 1943 .574,966 Great Britain Jan.29, 1946

